PRACTICE QUESTIONS

What molecule does this diagram represent? DNA

What is the circled part of the molecule called? A strand

How many strands does the DNA molecule have? Two

What is the circled part of the molecule called? Nucleotide

What is the circled part of the nucleotide called? Phosphate group

What is the circled part of the nucleotide called? Deoxyribose (sugar)

What is the circled part of the nucleotide called? Nitrogenous base

What is the circled part of the molecule called? Sugar-phosphate backbone

How many backbones does the DNA molecule have? Two

What is the circled part of the molecule called? Base pair

What is the circled part of the molecule called? Covalent bond

What is the circled part of the molecule called? Hydrogen bond

DNA is a , - stranded . long double polymer Structure

DNA tells ribosomes how to into . arrange amino acids protein Function R group R group R group R group

A nucleotide is a of DNA. monomer

There are nucleotides in DNA. 4

Nucleotides can join together in . any order

The in DNA determines the protein that is made (the “ .”) ATTACGACA = AGCGGATAT= GCCATAAGC= order of nucleotides genetic code

Diagram of a Nucleotide DNA = deoxyribose phosphate group nitrogenous base (contains phosphorus) (contains nitrogen) deoxyribose 5 (a -carbon ) sugar

Each DNA strand is held together by between the and groups of each nucleotide. bonds deoxyribose phsophate sugar “ - “ phosphate backbone GIVES STRUCTURE

Sugar-phosphate backbone Sugar-phosphate backbone

The two strands are held together by between the . bonds nitrogenous bases “ ” base pair GENETIC CODE

In DNA, always bonds with T, and C always bonds with ; this is called the - . G rule of base pairing

There are two types of bonds in the DNA molecule.

The bonds in the are very , to . covalent backbone strong prevent the genetic code from changing

The bonds holding the together are relatively … hydrogen base pairs weak

…which allows the two strands to during . separate replication

All 4 nucleotides have deoxyribose and a phosphate group, but they have different . nitrogenous bases Adenine Cytosine Guanine Thymine

A and G are (base has ). purines two rings Adenine Cytosine Guanine Thymine

Looks more like a pyramid C and T are (base has ). pyramidines one ring Adenine Cytosine Looks more like a pyramid Guanine Thymine Purines Pyrimidines

Purines always form with pyramidines. base pairs Pyrimidine Purine Pyrimidine Purine Purine Pyrimidine Purine Pyrimidine

The two strands in DNA are . Instead, they are to each other ( ). not identical complementary opposite

Use the DNA strand below to complete the complementary strand. G C G T T G T G C C G C A A C A C G

How did you know which nucleotides to put on the complementary strand? Base-pairing rules G C G T T G T G C C G C A A C A C G

Identify the circled nucleotide as a purine or a pyramidine, and defend your answer. One ring

Identify the circled nucleotide as a purine or a pyramidine, and defend your answer. Two rings

Identify the circled nucleotide as adenine or thymine, and defend your answer. Pyramidine

Identify the circled nucleotide as guanine or cytosine, and defend your answer. Purine

If the red nucleotide is guanine, what is the purple nucleotide? Cytosine Base-pairing rules G

Explain why it is incorrect to say that the two strands in a DNA molecule are identical to each other. Complementary opposite